Strain specific FGF21 expression analysis in wild type (WT) mice and B-hFGF21 mice by ELISA. Serum was collected from WT mice (+/+) and heterozygous B-hFGF21 mice (H/+) and analyzed by ELISA with FGF21 ELISA kit. Mouse FGF21 was detectable in WT mice (+/+) and heterozygous B-hFGF21 mice (H/+). Human FGF21 was detectable in WT mice (+/+) and heterozygous B-hFGF21 mice (H/+) due to the cross-reactivity of antibodies. Values are expressed as mean ± SEM.